Multi-point cooling system for a solar concentrator

ABSTRACT

A solar concentrator includes an optical member having a focal point. The optical member is configured and disposed to direct incident solar radiation to the focal point. A support member is positioned adjacent to the focal point of the optical member. A solar energy collector is supported upon the support member. The solar energy collector is positioned at the focal point of the optical member. A base member is positioned in a spaced relationship from the support member. The base member and the support member define a chamber section that is in a heat exchange relationship with the solar energy collector. The chamber section is configured to absorb and dissipate heat from the solar energy collectors.

BACKGROUND

The present invention relates to solar concentrators, and morespecifically, to a multi-point cooling system for a solar concentrator.

Solar power systems fall generally into two categories: fixed positionflat panel systems, and tracking concentrator systems. Fixed positionflat panel systems employ one or more stationary panels that arearranged in an area having an unobstructed view of the sun. As the earthrotates, the sun's rays move over the stationary panel(s) with varyingdegrees of intensity depending upon geographic location, time of day andtime of the year. In contrast, solar concentrator systems collect, andfocus the sun's rays onto one or more solar cells. Certain solarconcentration systems employ tracking systems that follow the sun's pathin order to enhance energy collection. Simply put, fixed position flatpanel systems represent a passive solar collection system, while solarconcentrator systems represent a more active energy collection system.

Solar concentrator systems utilizing photovoltaic cells typicallyoperate at or below about 500 suns concentration. Operating at highersun concentration levels creates cooling challenges. At present, solarconcentrator cooling systems are large unwieldy systems and/or possesslimited cooling capacity. Thus, one major constraint that limits solarconcentrator system is the ability to adequately cool the photovoltaiccells.

SUMMARY

According to one exemplary embodiment, a solar concentrator includes anoptical member having a focal point. The optical member is configuredand disposed to direct incident solar radiation to the focal point. Asupport member is positioned adjacent to the focal point of the opticalmember. A solar energy collector is supported upon the support member.The solar energy collector is positioned at the focal point of theoptical member. A base member is positioned in a spaced relationshipfrom the support member. The base member and the support member define achamber section that is in a heat exchange relationship with the solarenergy collector. The chamber section is configured to absorb anddissipate heat from the solar energy collectors.

According to another exemplary embodiment, a method of cooling a solarconcentrator includes absorbing heat from solar energy collectors into achamber section. The chamber section is arranged below, in a heatexchange relationship, the solar energy collectors.

Additional features and advantages are realized through the techniquesof the present invention. Other embodiments and aspects of the inventionare described in detail herein and are considered a part of the claimedinvention. For a better understanding of the invention with theadvantages and the features, refer to the description and to thedrawings.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

The subject matter which is regarded as the invention is particularlypointed out and distinctly claimed in the claims at the conclusion ofthe specification. The forgoing and other features, and advantages ofthe invention are apparent from the following detailed description takenin conjunction with the accompanying drawings in which:

FIG. 1 is a schematic plan view of a solar concentrator including amultipoint cooling system in accordance with an exemplary embodiment;and

FIG. 2 is a schematic plan view of a solar concentrator including amultipoint cooling system in accordance with another aspect of theexemplary embodiment.

DETAILED DESCRIPTION

With reference to FIG. 1, a solar concentrator constructed in accordancewith an exemplary embodiment is indicated generally at 2. Solarconcentrator 2 includes an optical member or lens 4 having a pluralityof focal points 6-8. A plurality of solar energy collectors 10-12 arepositioned at each of the respective focal points 6-8. With thisarrangement, incident solar radiation passing through optical member 4is guided to focal points 6-8 and, by extension, onto solar energycollectors 10-12. The solar energy collectors 10-12 convert the solarenergy into electrical energy. As will be discussed more fully below,solar energy collectors 10-12 take the form of triple junctionphotovoltaic concentrator cells that operate at high solarconcentrations, e.g., concentrations greater than 50 W/cm² (about 500suns). In accordance with one aspect of the exemplary embodiment, solarenergy collectors 10-12 can operate at concentrations levels as high as200 W/cm² (about 2000 suns) or more. As such, solar concentrator 2requires a cooling system that will absorb and dissipate heat generateat solar energy collectors 10-12 operating at such concentration levels.At this point it should be understood that while only three solar energycollectors are shown, solar concentrator 2 could include many more solarenergy collectors without departing from the scope of the claims.

In accordance with an exemplary embodiment, solar energy collectors10-12 are mounted to a multi-point cooling system 14. More specifically,solar energy collectors 10-12 are mounted to a support member 16 formedfrom a metal or ceramic material having a high heat dissipationco-efficient. In accordance with one aspect of an exemplary embodiment,support member 16 is formed from one or more of Aluminum Nitride (AlN),Aluminum Oxide (Al₂O₃), Nickel and Copper. Solar energy collectors 10-12are mounted to support member 16 via a corresponding plurality ofthermal interface members 17-19. In the exemplary embodiment shown, alayer of insulation is mounted to support member 16 about solar energycollectors 10-12. Electrical connections 23-25 extend from respectiveones of solar energy collectors 10-12 along insulation layer 20.Electrical connections 23-25 lead to an energy storage device (notshown).

In further accordance with the exemplary embodiment, multi-point coolingsystem 14 includes a base member 36. Support member 16 is mounted to abase member 36 via a peripheral wall 40. In a manner similar to thatdescribed above, base member 36 is formed from a metal or ceramicmaterial having a high heat diffusion co-efficient. Base member 36 isspaced from support member 16 so as to define a chamber section 44. Inaccordance with one aspect of the invention, chamber section 44 isfilled with a vapor formed from, for example, water or ammonia, thatenhances heat dissipation from solar energy collectors 10-12. Basemember 36 is also coupled to support member 16 via a plurality ofstructural supports 47-50. Each structural support 47-50 is covered by awicking material 52-55. In accordance with one aspect of an exemplaryembodiment, wicking material 52-55 is formed from sintered copperparticles or from a material having machined grooves. Wicking material52-55 enhances heat transferred from solar energy connector 10-12 intochamber section 44. In order to further enhance heat transfer, aplurality of nucleation membranes 59-61 is mounted to support member 16within chamber section 44. Each nucleation membrane 59-61 is positionedadjacent a corresponding one of solar energy collectors 10-12. Inaccordance with an aspect of an exemplary embodiment, nucleationmembranes 59-61 are formed from sintered copper particles arranged in abody formed from copper or aluminum. With this arrangement, vaportravels in wicking material 52-55 and or nucleation membranes 59-61.Heat from the vapor is dissipated through, for example, base member 36forming a condensate that returns to chamber section 44.

In order to facilitate heat energy transfer from chamber section 44,solar concentrator 2 includes a plurality of cooling fins 66 mounted tobase member 36. Cooling fins 66 transfer heat energy from chambersection 44 to be dissipated via air currents passing across base member36. In accordance with one aspect of the invention, heat energydissipation is further enhanced by a plurality of conduits 71-74extending through chamber section 44. Conduits 71-74 are configured anddisposed to absorb heat energy from chamber section 44. In accordancewith one aspect of the invention of the present embodiment, conduits71-74 are filled with a liquid that is circulated within chamber section74. The liquid absorbs heat energy that is passed to, for example, acooling medium after which the liquid is re-circulated back to chambersection 44.

Reference will now be made to FIG. 2, wherein like reference numbersrepresent corresponding parts in the respective use, in describinganother aspect of the exemplary embodiment. In accordance with theembodiment shown, solar concentrator 2 includes a finned cold plate 86mounted to base member 36. More specifically, finned cold plate 86includes a body 88 having a first substantially planner surface 90 andan opposing, second substantially planner surface 91. Firstsubstantially planner surface 90 is provided with a plurality of coolingfins 95 that dissipate heat energy in a manner similar to that describedabove. Second substantially planner surface 91 is attached to basemember 36 via a thermal interface member 98. Thermal interface member 98enhances energy transfer from base plate 36 to finned cold plate 86. Inaccordance with an aspect of an exemplary embodiment, cold plate 86 isformed from one of copper, aluminum or a high heat dissipationcoefficient ceramic material.

At this point, it should be understood that the exemplary embodimentsprovide a system for removing heat energy from a solar concentrator.That is, the present exemplary embodiments enable a solar concentratorto operate above 2000 suns while remaining cool. That is, in contrast toexisting systems that must operate substantially below 2000 suns, theexemplary embodiments provide sufficient cooling to enable so the solarconcentrator to operate at much higher solar concentration levels inorder to enhance energy conversion.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of the invention. Asused herein, the singular forms “a”, “an” and “the” are intended toinclude the plural forms as well, unless the context clearly indicatesotherwise. It will be further understood that the terms “comprises”and/or “comprising,” when used in this specification, specify thepresence of stated features, integers, steps, operations, elements,and/or components, but do not preclude the presence or addition of oneor more other features, integers, steps, operations, element components,and/or groups thereof.

While the preferred embodiment to the invention had been described, itwill be understood that those skilled in the art, both now and in thefuture, may make various improvements and enhancements which fall withinthe scope of the claims which follow. These claims should be construedto maintain the proper protection for the invention first described.

1. A solar concentrator comprising: an optical member having a focalpoint, the optical member being configured and disposed to directincident solar radiation to the focal point; a support member positionedadjacent the focal point of the optical member; a solar energy collectorsupported upon the support member, the solar energy collector beingpositioned at the focal point of the optical member; a base memberpositioned in a spaced relationship from the support member, the basemember and the support member defining a chamber section that is in aheat exchange relationship with the solar energy collectors, the chambersection being configured to absorb and dissipate heat from the solarenergy collectors.
 2. The solar concentrator according to claim 1,further comprising: a thermal interface member positioned between thesolar energy collector and the support member.
 3. The solar concentratoraccording to claim 1, further comprising: a nucleation membrane mountedto an underside of the support member adjacent the solar energycollector, the nucleation membrane enhancing thermal energy flow fromthe solar energy collector into the chamber section.
 4. The solarconcentrator according to claim 1, wherein the chamber section comprisesa vapor chamber.
 5. The solar concentrator according to claim 4, furthercomprising: a support element extending between the support member andthe base member within the chamber section.
 6. The solar concentratoraccording to claim 5, wherein the support element is formed from awicking material, the support element enhancing thermal energy transferbetween the solar energy collector and the chamber section.
 7. The solarconcentrator according to claim 1, further comprising: a plurality ofheat dissipating fins mounted to an external surface of the base member.8. The solar concentrator according to claim 1, further comprising: aplurality of conduits extending through the chamber section, theplurality of conduits absorbing heat from the chamber section receivedfrom the solar energy collectors.
 9. The solar concentrator according toclaim 8, wherein the plurality of conduits transport a heat exchangemedium through the chamber section.
 10. The solar concentrator accordingto claim 9, wherein the heat exchange medium is a liquid.
 11. The solarconcentrator according to claim 1, further comprising: a finned coldplate mounted to the base member.
 12. The solar concentrator accordingto claim 11, further comprising: a thermal interface material positionedbetween the finned cold plate and the base member.
 13. A method ofcooling a solar concentrator, the method comprising: absorbing heat fromsolar energy collectors into a chamber section, the chamber sectionbeing arranged, in a heat exchange relationship, below the solar energycollectors.
 14. The method of claim 13, further comprising: absorbingthe heat into a plurality of conduits passing through the chambersection.
 15. The method of claim 14, further comprising: passing theheat into a fluid passing through the plurality of conduits.
 16. Themethod of claim 13, further comprising: dissipating the heat from thechamber section though a plurality of cooling fins.
 17. The method ofclaim 13, further comprising: passing the heat from the solar energycollector to the chamber section through a thermal interface member. 18.The method of claim 13, further comprising: absorbing the heat into avapor present within the chamber section.
 19. The method of claim 18,further comprising: passing the heat from the solar energy collectorinto the vapor through a nucleation membrane.
 20. The method of claim18, further comprising: absorbing the heart into a wicking materialprovided on a support in the chamber section.